Width-maintaining cylinders are used in textile machines, especially in weaving machines or in machies for inspecting cloth. These width-maintaining devices have the function of guiding the fabric on the weaving machine so that it always has a constant width.
In this process the inclined wheels of the width-maintaining cylinder have spikes on their outer periphery which catch in the fabric, constantly push the fabric outwards as the wheels are turning, and then detach themselves again from the fabric.
The width-maintaining cylinders are located on both sides of the weaving machine and ensure that the fabric produced is held at a constant width.
FIG. 1A shows shematically a weaving machine. From the warp beam 1 the warp threads are guided over the carding beam 2, through the strand eyelets 3 of the shafts 4. After passing through the plate 5 they are crossed with the shuttle thread carried in the weaving shuttle 7. This operation causes the formation of the fabric. This fabric passes over the breast beam 9 to the goods beam 6. As apparent, during the manufacture of the fabric, the web of fabric is held at the same width by width-maintaining cylinders which are located on both sides of the weaving machine, so that a taut shape is produced.
FIG. 1B shows a conventional width-maintaining cylinder. Width-maintaining cylinders of known type have the drawback that owing to their construction they have the inevitable tendency to distort as they are being fitted into the weaving machine. This inevitable tendency to distortion is described below with reference to FIG. 1C of the drawings.
According to FIG. 1C the width-maintaining cylinder has a support 10 which is provided at its free end with a closed cap 11 as tensioning element, and at its other end with a thread 12. A number of bearings 13 are arranged next to one another on the support 10. Each bearing is provided with a flange 14 and a small wheel 15 is rotatably mounted on each bearing. The small wheels 15 are provided with spikes 16. Instead of spikes, rubber rings 17 also many be used which likewise draw the fabric outwards through friction and thus hold it at a constant width.
The contact surface 20 of a bearing 13 to the flange 14 of the adjacent bearing is at an angle to the longitudinal axis of the support 10.
The width-maintaining cylinder is secured through an opening by a nut 19 to the weaving machine 18.
By tightening the nut 19 the bearings 13 with the flanges 14 are pushed together via a tapered washer 52, resulting in an axial tensioning force P.sub.v. The magnitude of the tensioning force is dependent on the diameter of the support 10, on the type of thread 12, on the friction coefficients of the nut 19 on the surface of the weaving machine 18 and on the tightening torque with which the nut 19 is tightened. Practical findings have shown that the tensioning force P.sub.v in the case of width-maintaining cylinders having a support diameter of 8 mm is approximately 800 to 1,000 kiloponds.
The axial tensioning force P.sub.v is divided into a normal force P.sub.N and into a shearing force P.sub.Q. The shearing force P.sub.Q is about 300 kiloponds when the flange 14 is inclined at 70.degree. to the longitudinal axis of the support 10. Since the resistance to bending of the support 10 is smaller than the shearing force P.sub.Q (about 1/5th), a distortion of the part 10 and thus of the width-maintaining cylinder is inevitably produced so that its ability to function is no longer guaranteed under all circumstances.
It is the task of the present invention to provide a width-maintaining cylinder of the type referred to initially which, with a simple construction, ensures in every case that regardless of the tensioning force as the tensioning elements are tightened, a distortion of the width-maintaining cylinder can be prevented satisfactorily.
This problem is solved according to the invention in that the contact surfaces of the bearing which can be pressed against one another are at right angles to the longitudinal axis of the support 10. This produces the advantage that when tightening the nut, an axial tensioning force is produced which is effective at right angles upon the contact surfaces which may be pressed against one another. Thus no forces P.sub.N and P.sub.Q occur which could lead to a distortion of the width-maintaining cylinder. Thus in every case the complete functional reliability of the width-maintaining cylinder is ensured, regardless of the tightening torque of the tensioning elements.
Further advantages and features of the present invention are apparent from the sub-claims and from the following description of the figures.